Condylar Cartilage Of Rats Research Articles

A Non-Invasive Method for Generating the Cyclic Loading-Induced Intra-Articular Cartilage Lesion Model of the Rat Knee

Here, we present the cyclic loading-induced intra-articular cartilage lesion model of the rat knee, generated by 60 cyclic compressions over 20 N, resulting in damage to the femoral condylar cartilage in rats.

Fibrocartilage Stem Cells in the Temporomandibular Joint: Insights From Animal and Human Studies.

Temporomandibular disorders (TMD) are diseases involving the temporomandibular joint (TMJ), masticatory muscles, and osseous components. TMD has a high prevalence, with an estimated 4.8% of the U.S. population experiencing signs and symptoms, and represents a financial burden to both individuals and society. During TMD progression, the most frequently affected site is the condylar cartilage. Comprising both fibrous and cartilaginous tissues, condylar cartilage has restricted cell numbers but lacks a vascular supply and has limited regenerative properties. In 2016, a novel stem cell niche containing a reservoir of fibrocartilage stem cells (FCSCs) was discovered in the condylar cartilage of rats. Subsequently, FCSCs were identified in mouse, rabbit, and human condylar cartilage. Unlike mesenchymal stem cells or other tissue-specific stem/progenitor cells, FCSCs play a unique role in the development and regeneration of fibrocartilage. More importantly, engraftment treatment of FCSCs has been successfully applied in animal models of TMD. In this context, FCSCs play a major role in the regeneration of newly formed cartilage. Furthermore, FCSCs participate in the regeneration of intramembranous bone by interacting with endothelial cells in bone defects. This evidence highlights the potential of FCSCs as an ideal stem cell source for the regeneration of oral maxillofacial tissue. This review is intended to detail the current knowledge of the characteristics and function of FCSCs in the TMJ, as well as the potential therapeutic applications of FCSCs. A deep understanding of the properties of FCSCs can thus inform the development of promising, biologically based strategies for TMD in the future.

Histological structure of the mandibular condylar cartilage in rats of various age after 60-day intake of epichlorohydrin

Histological structure of the mandibular condylar cartilage in rats of various age after 60-day intake of epichlorohydrin

Influence of sleep deprivation on expression of MKK4 and c-fos in the mandibular condylar cartilage of rats

The aim of this study was to investigate the changes in expression of mitogen-activated protein kinase kinase 4 (MKK4) and c-fos in the mandibular condylar cartilage of rats that had been subjected to sleep deprivation. One hundred and twenty female Wistar rats were randomly divided into 6 groups with 20 in each: sleep deprivation for 2 days, 4 days, 6 days, and 8 days, large-platform controls, and cage controls. After sleep deprivation by the modified multiple platform method the sleep-deprived rats were killed. The large-platform and cage control rats were killed at the same time as the rats deprived of sleep for 8 days. Haematoxylin and eosin were used to record the morphological changes in cartilage, and immunohistochemistry and real-time quantitative polymerase chain reaction (PCR) were used to detect the expression of MKK4 and c-fos. Pathological alterations were apparent after 6 and 8 days of sleep deprivation. Compared with control groups, the expression of MKK4 in the sleep-deprived groups was lower, while that of c-fos was higher. As the duration of sleep deprivation increased, the expression of MKK4 decreased. These results indicate that the variation in expression of MKK4 and c-fos may be correlated with pathological changes induced by sleep deprivation in mandibular condylar cartilage in rats.

Changes in the expression of aromatase, estrogen receptor α and β in mandibular condylar cartilage of rats induced by disordered occlusion

BackgroundEstrogens play an important role in modulating the morphology and function of temporomandibular joints (TMJs), which is suggested to act via estrogen receptors (ERs). The present study was to investigate the expression of aggrecan, collagen type II (Col II), Col X, aromatase, ERα and ERβ in degenerative changes of mandibular condylar cartilage.MethodsForty male and 40 female 8-week-old rats were enrolled in this study. In experimental groups, the disordered occlusion was created by moving the first molars mesially and the third ones distally. Immunohistochemistry and real-time PCR were performed at the end of the second or fourth week.ResultsDegenerative changes, characterized by interrupted continuity of hypertrophic layer, pyknotic and eosinophilic lesion with few nuclei, areas filled with eosinophilic nuclei, were observed in more joints from female experimental groups than male ones. However, thickening changes in hypertrophic layer were only found in male experimental groups. The gene expression of Col II, Col X and aggrecan increased in 4-wk male experimental subgroup (both P < 0.01), but decreased in 2-wk and 4-wk female subgroups (P < 0.05). The gene expression of ERα decreased in 2-wk male and female experimental subgroups (both P < 0.01), however, that of ERβ increased except the 2-wk female experimental subgroup (all P < 0.01). The expression of aromatase decreased in both male and female experimental subgroups (all P<0.01).ConclusionsMandibular condylar cartilage responses differently to the disordered occlusion in male and female rats. The levels of locally synthesized estrogen, ERα and ERβ may have limited attribution, if any, to the sex-specific cartilage response.

The effect of posterior tooth loss on the expression of type II collagen, IL-1β and VEGF in the condylar cartilage of growing rats

ObjectiveThe aim of this study was to evaluate the effect of unilateral and bilateral loss of posterior occlusal support on the expression of type II collagen, interleukin-1β and VEGF in the condylar cartilage of growing rats. DesignThirty female Wistar rats (5 weeks old) were randomized into three groups: control, unilateral extraction of mandibular molar teeth, bilateral extraction of mandibular molar teeth. Animals were sacrificed 8 weeks after tooth extraction and the temporomandibular joints were prepared for immunohistochemical analysis. ResultsBilateral molar extraction increased the expression of interleukin-1β (P<0.01) and VEGF (P<0.01), while unilateral extraction increased the expression of interleukin-1β (P<0.05) and type II collagen (P<0.01). The expression of VEGF was higher on the extracted than on the non-extracted side (P<0.01) after unilateral extraction. ConclusionLoss of posterior occlusal support alters the expression of type II collagen, interleukin-1β and VEGF in the condylar cartilage of rats. The expression pattern of these proteins is different when loss of occlusal support was bilateral or unilateral, including differences between extracted and non-extracted sides.

Aging change of mandibular condyle in female F344/N rat

To ascertain whether laboratory rats represent an adequate animal model for aging oral cavity research, this study focused on the morphology of the mandibular condyle. Aging changes of cartilaginous conformation and shape of the mandibular condyles were analyzed in female F344/N rats. In the condylar cartilage, articular, proliferative cell and hypertrophic cell layers were observed in 1-month-old (M) rat, whereas flattened cell layer was notable at 2 M. A mature cell layer was observed in the condylar cartilage of rats at 7.7 M and over. Deranged cartilaginous layers and thinning articular layer were observed in 30.9 M rat. The sagittal length of the condyle decreased, whereas the frontal one increased with aging and/or age. There were three phases in the transition patterns of the size of the condyle, which seemed to correspond to the respective growing, aging and senescence phases in the rat. The results suggested that degenerative change of condylar cartilage in rat was similar to that in human, whereas change of the shape of the condyle was different between rat and human, caused by a different pattern of mastication.

Age-related changes in gene expression patterns of matrix metalloproteinases and their collagenous substrates in mandibular condylar cartilage in rats.

Matrix metalloproteinases (MMPs) have been implicated in physiological cartilage matrix remodelling as well as in pathological and invasive extracellular matrix remodelling of tissue. Age-related changes in the gene expression patterns of MMPs in mandibular condylar cartilages (MCCs) were analysed. We examined the gene expression patterns of Mmp-8 and -13 and their substrates, Col1a1, Col2a1 and Col10a1, in MCC of growing and ageing rats. Temporomandibular joints of male Wistar rats aged 4, 8, 16 and 32 weeks were subjected to in situ hybridization analysis. Histologically, MMCs showed characteristics of growth plate cartilage at ages 4 and 8 weeks, and more closely resembled articular cartilage thereafter. Mmp-8 was expressed in the cells in all cartilaginous cell layers at ages 4 and 8 weeks, and then was localized only in the mature cells at ages 16 and 32 weeks. Whereas Mmp-13 expression was limited to the lowermost hypertrophic chondrocytes in the growth stage, mature chondrocytes instead of hypertrophic chondrocytes expressed Mmp-13 in adult non-hypertrophic MCC. Because Mmp-8 and -13 expression overlapped with Col2a1 and Col10a1, chondrocytes could play a pivotal role in degradation as well as production of the cartilaginous matrix in MCC.

Effects of cyclosporin A on the mandibular condylar cartilage in rats

Twenty, 5-week-old, male, Sprague–Dawley rats were divided into a control and a cyclosporin A (CSA) group for evaluating effects of the drug on condylar cartilage. Animals in the treatment group daily received CSA (15 mg/kg body wt) in mineral oil by gastric feeding over a 4-week observation interval. Control animals received mineral oil only. Five animals from each group were killed at weeks 2 and 4 of study. After histological processing, five tissue sections from the mid-region of the condyle were selected and examined. Three compositional zones (articular fibrous, proliferative, and hypertrophic) of the superior, posteriosuperior and posterior regions of the condylar cartilage were evaluated by light microscopy. At week 2, total condylar cartilage thickness was similar in the CSA and control groups, but the thickness of each zone was altered in CSA-treated animals, including a decrease of the fibrous and proliferative zones and an increase in hypertrophic zone compared to control ( P<0.05). At week 4, CSA-treated animals exhibited overall decreased cartilage thickness, including decreased thickness of each zone compared to control ( P<0.05). The results suggest that CSA has an inhibitory effect on the maturation of the mandibular condyle in rats.

Effect of dietary consistency on matrix synthesis and composition in the rat condylar cartilage.

Little is known of how the matrix of the condylar cartilage of the mandible changes in response to an alteration in local biomechanical circumstances, although this has been a habitual focus of studies of articular cartilage in the orthopedic literature. This study was formulated to investigate (1) whether matrix changes would occur in the condylar cartilage of rats fed a diet of soft consistency, a circumstance which would presumably reduce articular forces at the mandibular joint; (2) whether these changes, once established, could be reversed by restoring a diet of hard rat pellets, and (3) if these changes were localized to a particular region(s) of the cartilage. In the first experiment, male Sprague-Dawley rats were provisioned with either a soft, mushy diet or hard rat pellets beginning at weaning and subsequently sacrificed at 44 days of age. In the second experiment, all animals were initially given the soft diet, but in half a normal hard diet was reinstituted for 7 days prior to sacrifice at 44 days of age. In the third experiment, cartilages from rats fed soft and hard diets were subdivided into a superior fraction (that portion directly opposite the cranial articulation) and a posterior fraction. The results of experiment 1 showed the water content of the condylar cartilage to be significantly reduced in the soft-diet group, as well as one measure of [35S]uptake into sulfated glycosaminoglycans ([35S]sulfate dpm/micrograms uronic acid). Both wet and dry tissue weights of the condylar cartilage were greatly reduced in rats fed a soft diet.(ABSTRACT TRUNCATED AT 250 WORDS)